1. Field of the Invention
The invention relates to an overload release clutch for the transmission of rotary movements between shafts, having two axially disengageable clutch halves borne by a hub, one coupling half being non-rotatably connected to the hub and the other clutch half being rigidly connected axially to the hub, a spring arrangement being provided which has a snap-over characteristic and which acts with an adjustable axial force on the axially movable clutch half in the engaged state, the spring arrangement consisting of a concentric ring connected to the axially movable clutch half, and radially directed bearing elements which are pivotably disposed at an inclination to the axial plane of the clutch on the ring and the hub disposed at a radial distance inside the ring.
2. Discussion of Prior Art
In a prior art overload release clutch the torque is transmitted from the driven shaft and the hub connected thereto and the other clutch half by means of a positive connection to the other clutch half which is connected to the output. If overloading occurs, the positively interengaging elements of the connection between the clutch halves which, for example, can be constructed in the form of a crown gear connection, produce an axial movement of the other clutch half in relation to the axially fixed clutch half, a relative movement of the clutch halves also taking place in the peripheral direction. The axial movement of the other clutch half is counteracted by the force of a cup spring whose characteristic is so adjusted that the spring can occupy two stable axial positions, the transition from one stable position to the other taking place when the snap-over point on the spring characteristic is exceeded. If, after the snap-over point has been exceeded the spring arrangement occupies its other stable position, the two clutch halves are permanently separated from one another. According to the prior art, in which the spring arrangement is formed by two cup springs, the appropriate axial prestressing force of the spring arrangement is adjusted by means of a release spring which can be adjusted via an axially adjustable sleeve. However, constructionally this prior art spring arrangement is relatively expensive, since to ensure reliable operation, not only the cup springs are required, but various other constructional elements also, for example, a spacer ring between the cup springs or a securing ring.
In one prior art overload release clutch of the kind specified the expense of the construction is substantially lower (German Patent Specification No. 28 21 029 A1, U.S. Pat. No. 4 004 667). In that clutch the bearing elements consist of resilient strips or a pack of lamellar springs clamped between a rigid bearing on the hub and a rigid concentric ring. To change over the clutch, these elements must be deformed by being moved with radial upsetting out of the prestressed position on one side of the neutral plane into a prestressed position on the other side thereof. Such stressing is not optimum for the service life of the resilient strips. Moreover, such constructions are at best suitable for large diameters and the transmission of relatively low torques.